So I successfully managed to get logging working after upgrading to 3.0.0 from an old OpenX installation, and it was running for a few days. I then saw the upgrade to 3.0.2 and went through the incredibly laborious process of upgrading, only to discover after a few days that it wasn't logging statistics any more! So I disabled and re-enabled the plugins, uploading the zips from a fresh copy of 3.0.2.
Today I discovered that when I disabled the plugin Revive dropped the old statistics tables. Deleted my data! So then I recreated the tables and it seems to be logging data.
So, first I would assume that an ad delivery system should have logging built in. Then, when I disable a plugin I don't want my data deleted. Ever!
It seems like a lot of people have had problems with upgrade and logging. I would hope that the next version should have an automatic upgrade, and not break all the plugins. I can't afford to have missing statistics either, since we depend on that for billing clients.